ML17305B754

Provides History of Process Radiation Monitor RT-204 as Monitor Relates to Unit 2 License Condition & Current Status of Open Startup Test Issue for Monitor.Until Monitor Replaced,Portable Monitoring Instrumentation Will Be Used

ML17305B754
Person / Time
Site:	Palo Verde
Issue date:	09/25/1991
From:	Conway W ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
161-04180-WFC-J, 161-4180-WFC-J, NUDOCS 9110010060
Download: ML17305B754 (8)

Text

REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSION NBR:9110010060 DOC.DATE: 91/09/25 NOTARIZED: NO DOCKET FACIL:STN-50-528 Palo Verde Nuclear Station, Unit 1, Arizona Publi 05000528 STN-50-529 Palo Verde Nuclear Station, Unit 2, Arizona Publi 05000529 STN-50-530 Palo Verde Nuclear Station, Unit 3, Arizona Publi 05000530 AUTH.NAME AUTHOR AFFILIATION CONWAY,W.F.

Arizona Public Service Co.

(formerly Arizona Nuclear Power RECIP.NAME RECIPIENT AFFILIATION Document Control Branch (Document Control Desk)

SUBJECT:

Provides history of process radiation monitor RT-204 as monitor relates to Unit 2 license condition

& current status of open startup test issue for monitor. Until monitor replaced, portable monitoring instrumentation will be used.

DISTRIBUTION CODE: A001D COPIES RECEIVED:LTR ENCL 10 SIZE:

TITLE: OR Submittal: General Distribution D

NOTES:STANDARDIZED PLANT Standardized plant.

Standardized plant.

RECIPIENT ID CODE/NAME PD5 LA TRAMMELL,C INTERNAL: ACRS NRR/DET/ESGB NRR/DST 8E2 NRR/DST/SICB8H7 NUDOCS-ABSTRACT OGC/HDS1 RES/DSIR/EIB EXTERNAL: NRC PDR NOTES:

COPIES LTTR ENCL RECIPIENT ID CODE/NAME PD5 PD THOMPSON,M NRR/DET/ECMB 7D NRR/DOEA/OTSB11 NRR/DST/SELB 7E NRR/DST/SRXB 8E OC/WEHB G

01 NSIC COPIES LTTR ENCL 1

A 05000528 05000529 05000530 D

D NOTE TO ALL"RIDS" RECIPIENTS:

D D

PLEASE HELP US TO REDUCE WASTE! CONTACT THE DOCUMENT CONTROL DESK, ROOM Pl-37 (EXT. 20079) TO ELIMINATEYOUR NAME FROM DISTRIBUTION LISTS FOR DOCUMENTS YOU DON'T NEED!

TOTAL NUMBER OF COPIES REQUIRED:

LTTR 27 ENCL

0 l

Arizona Public Service Company P.O. BOX 53999

~

PHOENIX, ARIZONA85072<999 WILLIAMF. CONWAY EXECUTIVEVICEPRESIDENT NUCLEAR 161-04180-WFC/JMQ September 25, 1991 Docket Nos.

STN 50-528/529/530 U. S. Nuclear Regulatory Commission Attn:

Document Control Desk Mail Station Pl-37 Washington, D.

C.

20555

References:

A)

Letter from E.

E.

Van Brunt, APS to G.

W. Knighton, U.

S.

Nuclear Regulatory Commission, ANPP-34129, "Justification for Interim Operation Related to the Radiation Monitors," dated November 29, 1985 B)

Letter from E.

E.

Van Brunt, APS to G.

W. Knighton, U.

S.

Nuclear Regulatory Commission, ANPP 36152, "License Condition 2.C.(1).8," dated April 15, 1986 C)

Letter from J.

G.

Haynes, APS to U.

S.

Nuclear Regulatory Commission, Document Control Desk, '161-00290-JGH, "Startup Report Supplement 2," dated June 18, 1987

Subject:

Palo Verde Nuclear Generating Station (PVNGS)

Units 1, 2, and 3

Process Radiation Monitor RT-204 File:

91-131-419; 91-056-026 This letter provides the history of the Process Radiation Monitor (PRM) RT-204 as it relates to the Unit 2 License Condition and the current status of the open startup test issue for PRM RT-204.

Arizona Public Service Company (APS) committed in Reference A to have RT-204 operable by initial criticality.

This was a Unit 2 low power and full power (NPF-46 and NPF-51, respectively)

License Condition.

Reference B defined the term "operable" for non-technical specification monitors, such as RT-204 as the monitors have successfully completed preoperational tests and the monitors have been placed in service."

RT-204 has successfully completed its preoperational test and via a Calibration Work Order, the monitor was energized, calibrated, setpoints

entered, and the monitor isolation valves were opened by May 1, 1986.

The completion of the preoperational test and Calibration Work Order is necessary to consider the monitor capable of performing its intended function or meeting the term "placed in service."

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S. Nuclear Regulatory Commission Attn: Document Control Desk Process Radiation Monitor RT-204 Page 2

Reference C stated that the operation of the PRM in Unit 2 was not verified during Power Ascension Testing, and provided several commitments, some of which were to be implemented by the first refueling outage for Unit 2.

These commitments were to:

1) repair the check valve associated with the PRM during the first planned outage;

2) conduct a design review of the subject

PRM, and implement any modifications identified by the design review during the Unit 2 refueling outage;

3) test the PRM in accordance with CESSAR, Section 14.2.12.5.5, and 4) submit a summary report to the NRC following the satisfactory completion of the testing of the PRM.

APS has addressed the commitments in the referenced letter as follows:

1)

The check valve, which provides bypass around the reactor coolant sample line, was repaired because it prevented the proper amount of flow from reaching the PRM.

The low flow resulted in'ncreasing plate out of antimony and other activated corrosion products on the PRM sample tube walls, thereby increasing the background count rate and degrading the monitor sensitivity.

However, this repair did not return the monitor to proper functioning status.

2) 3)

A number of modifications were pursued to make the PRM functional.

Examples of these modifications included adjusting the detector mounting bracket, reducing the sample volume measured by changing the sample tubing size on the detector

skid, balancing the flow rate through the sample system by repairing the check valve, and evaluating the use of a

smaller detector crystal in order to desensitize the monitor.

These modifications were attempted during the first two refueling outages, but proved unsuccessful in meeting the full functi.onal requirements of the monitor.

Because the PRM has not yet been

replaced, testing in accordance with CESSAR Section 14.2.12 '.5, willbe performed after replacement.

4)

A summary report will be submitted following the satisfactory completion of the testing of the PRM.

The PRM is designed to provide information on both the long-term trends and rapid changes in the level of radioactivity in the reactor coolant.

The monitor is used to provide a qualitative indication of reactor coolant activity and provide early detection of fuel cladding failure.

The PRM is utilized during normal plant operations (Mode 1) only.

It is not required per the Technical Specifications or Regulatory Guide 1.97.

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v 161-04180-WIlMQ September 25, 1991 U.

S. Nuclear Regulatory Commission Attn: Document Control Desk Process Radiation Monitor RT-204 Page 3

Since the modifications to make the PRM operable were unsuccessful, APS plans to replace the'RMs in the three, units during future refueling outages, beginning with the Unit 3 third refueling outage in 1992 (The PRM willbe installed in Unit 3 during the third refueling outage, but will not be fully functional until the fourth refueling outage,.

This is to ensure that all areas of potential concern have been thoroughly examined.),

the Unit, 2 fourth refueling outage in 1993, and the Unit 1 fourth refueling outage i'n 1993.

As compensatory action, until'he subject monitor is functional, APS will use portable radiation monitoring, instrumentation to qualitatively assess changes in fuel integrity.

These monitors will provide annunciation and continuous indication in the control

room, and will satisfy the general functional requirement of assessing fuel integrity as described in the UFSAR.

However, the same monitors are also used as part of the Pre-planned Alternate Sampling Program (PASP) and for area monitor detector calibrations.

Therefore, in the unlikely event that the portable monitor is required for the PASP or detector calibrations, it may be temporarily removed from monitoring letdown activity.

The portable radiation monitoring instrumentation was installed on August 30, 1991.

NUREG-0401 states, "Experience from operating reactors has not identified any event or mechanism that might give rise to sudden failures of large numbers of fuel elements during normal operation."

NUREG-0401 further states, a

sensitive fuel failure detection system with a modest response time, along with the other more rapid primary system sensors that would detect accident conditions, are adequate to give an early warning under almost all circumstances and allow a timely response to degrading fuel conditions."

Therefore, based on NUREG-0401, the compensatory measures and corrective actions for the PRM are justified.

If you should have any questions or require additional information, please contact Michael E. Powell of my staff at (602) 340-4981.

Sincerely, WFC/JMQ/j mq cc:

J.

B. Martin D.

H.

Coe A. C. Gehr A. H. Gutterman

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